Abstract

Cetacean occurrence in the Chukchi Sea is seasonal and primarily driven by annual sea ice retreat and prey occurrence in spring through fall. Humpback whales (Megaptera novaeangliae), fin whales (Balaenoptera physalus), and minke whales (Balaenoptera acutorostrata), although often found in polar waters elsewhere, are not common in the eastern Chukchi Sea, and here are referred to as “subArctic” species. Increasing numbers of these subArctic cetacean species were documented during aerial surveys in the eastern Chukchi Sea (67°–72°N, 157°–169°W) in July–October 2008–2016. The majority (78%) of these sightings occurred on the continental shelf in the south-central Chukchi Sea (67°–69°N, 166°–169°W) in August and September. During similar aerial surveys in 1982–1991, there was a complete lack of sightings of subArctic species. The disparity in sightings between the two time periods could be due to increased marine mammal survey effort in recent years during the months when subArctic cetacean species would be expected to occur, population recoveries from commercial whaling, climate change, or, most likely, a combination of all three.

Notes

Acknowledgements

The Aerial Surveys of Arctic Marine Mammals (ASAMM) project was funded by the U.S. Department of the Interior, Bureau of Ocean Energy Management (BOEM), Alaska Outer Continental Shelf Region, Anchorage, Alaska through Inter-agency Agreements M08PG20023, M11PG00033, and M16PG00013 with the Alaska Fisheries Science Center (AFSC) as part of the BOEM Alaska Environmental Studies Program. ASAMM was supported by Charles Monnett, Jeffrey Denton, and Carol Fairfield (BOEM CORs). At the AFSC Marine Mammal Laboratory, additional support was provided by Robyn Angliss, Stefan Ball, Phil Clapham, Mary Foote, Nancy Friday, Dave Rugh, Kim Shelden, Janice Waite, Joanne Wejak, and other administrative personnel. At the Joint Institute for the Study of the Atmosphere and Ocean, support was provided by Amy Kennedy, Julie Mocklin, and administrative personnel. Clearwater Air, Inc., the National Oceanic and Atmospheric’s Aircraft Operations Center, and their pilots and mechanics kept us airborne and safe. Real-time flight following via satellite link was provided by numerous individuals in the Department of the Interior. Programing support was provided by Mike Hay (XeraGIS). Numerous dedicated observers have enthusiastically participated in these surveys. Our sincerest thanks to all!

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